COi. 


UNIVERSITY  OF  CALIFORNIA. 


AGRICULTURAL   EXPERIMENT   STATION. 
BERKELEY,   CAL. 

E.  W.  HILGARD,  Director.  BULLETIN    No.   US. 


Remedies  for  Insects  and  Fnngi. 


DECEMBER,   1896. 


UNIVERSITY  OF  CALIFORNIA 
AGRICULTURAL  EXPERIMENT  STATION 


(Correction  and  Supplement  to  Bulletin   115.) 

This  sheet  is  published  in  response  to  numerous  inquiries  for  formulas 
not  included  in  Bulletin  115,  recently  issued  by  this  Station, 
and  for  the  purpose  of  correcting  quite  an  important  typo- 
graphical error  in  the  above-mentioned  bulletin. 

C.   W.   Woodworth. 


CORRECTION. 


Oil  page  12,  lines  12  and  13,  the  formula  for  the  Lime,  Salt,  and 
Sulphur  Mixture  should  read  :  "The  proportions  are  about  6  pounds 
of  lime,  2  of  salt,  and  3  of  sulphur,  for  10  (not  66)  gallons." 

SUPPLEMENT. 

Professor  Hilgard' s  Sulphid  of  Potash  Wash. — This  has  proven  so 
useful  for  removing  moss  from  trees  that  a  number  have  requested  it. 
The  formula  is  as  follows:  Caustic  soda  (980),  1  pound;  commercial 
potash,  1  pound  ;  sulphur,  3  pounds.  Boil  together  one  hour.  Dis- 
solve 20  pounds  whale  oil  soap  (8o°)  in  hot  water;  add,  and  boil  one 
half-hour.      Dilute  to  100  gallons.     Apply  hot. 

Professor  Pierce" s  Bordeaux  Mixture. — This  is  the  modification  of 
the  Bordeaux  mixture  with  which  Professor  Pierce  had  such  good 
results  against  the  curl-leaf  of  the  peach.  It  contains  double  the 
amount  of  lime  generally  recommended.  The  formula  is  as  follows  : 
5  pounds  of  Milestone,  10  pounds  of  lime,  for  45  gallons.  Prepare  in 
the  same  manner  as  other  Bordeaux  mixtures.  For  curl-leaf  apply 
from  one  to  three  weeks  before  buds  open. 

Paris  Green  and  Bordeaux  Mixture. — We  neglected  to  state  in  the 
Bulletin  that  when  it  is  desirable  to  use  these  two  washes  at  the  same 
time,  as  for  codlin  moth  and  scab,  the  green  may  be  stirred  into  the 
Bordeaux  mixture  at  the  usual  proportion,  i.e.,  1  pound  to  200  gallons. 


Bkrkki.Hy,  Cal.,  March  9,  1S97. 


Digitized  by  the  Internet  Archive 

in  2012  with  funding  from 

University  of  California,  Davis  Libraries 


http://www.archive.org/details/remediesforinsec115wood 


REMEDIES  FOR  INSECTS  AND  FUNGI 

By  C.  W.  Woodworth. 


It  is  very  important  that  every  one  who  has  the  care  of  crops,  whether 
of  garden,  orchard,  or  field,  should  have  a  clear  idea  of  the  remedies 
available  for  preventing  the  injuries  due  to  insects  and  fungi.  Not  only 
must  one  know  how  to  make  and  apply  the  remedies,  but  it  is  equally 
essential  that  he  should  fully  understand  when  to  apply  and  when  not 
to  apply.  It  is  safe  to  say  that,  even  in  California,  where  this  matter 
has  been  agitated  for  so  many  years,  in  only  a  very  small  fraction  of  the 
cases  where  injury  might  be  prevented  is  the  proper  treatment  made. 
On  the  other  hand,  it  may  also  be  said  that  when  a  treatment  is  made 
it  is  often  of  no  effect,  and  a  waste  of  time  and  money.  Careful  obser- 
vation of  the  practices  in  this  State  in  reference  to  treating  insects  and 
fungi  makes  it  appear  that  fully  half  of  what  it  now  costs  to  treat  our 
crops  is  wasted. 

Mistakes  Made. — The  chief  mistakes  made  in  applying  remedies  are 
the  following: 

First — Applications  are  often  made  when  there  is  absolutely  no  need 
for  treatment — when  there  is  nothing  to  destroy  nor  to  prevent; 

Second — Applications  are  often  wrongly  timed;  either  applied  before 
there  is  any  chance  to  produce  good  results,  or  after  the  injury  has  all 
been  done; 

Third — Often  the  wrong  kind  of  an  application  is  chosen  for  the 
particular  trouble,  so  that  no  results  can  follow; 

Fourth-1- Applications  are  often  made  for  troubles  that  are  incurable 
by  any  known  practical  method; 

Fifth — Expensive  methods  are  employed  when  cheaper  ones  will  ac- 
complish the  results,  both  as  regards  the  material  used  and  the  labor 
employed. 

There  is  no  reason  why  these  might  not  to  a  great  degree  be  avoided. 
Mistakes  of  judgment  will  always  cause  loss  in  this  as  in  any  other 
operation,  but  there  is  no  reason  why  these  mistakes  of  ignorance  should 
be  allowed  to  amount  to  half  the  cost  of  such  applications.  In  the 
following  pages  we  will  attempt  to  present,  in  a  brief  compass,  the  more 
important  points  to  be  considered  in  the  treatment  of  plants.  But  it 
should  be  distinctly  recognized  that  local  experience  and  experiment  is 
the  only  real  guide  for  successful  practice.  Especially  in  this  State, 
where  our  conditions  are  so  wonderfully  diversified,  is  it  impossible  to 
formulate  detailed  programs  or  calendars  of  operations  which  will  be  of 
general  value. 

Any  one  with  ordinary  intelligence,  however,  who  is  willing  to 
observe  and  think,  has  no  excuse  for  falling  into  the  mistakes  indicated 
above. 


-  4 


CLASSES   OF  PESTS. 


Almost  all  the  serious  pests  that  attack  plants  are  either  insects  or 
fungi.  These  we  may  classify,  according  to  their  way  of  attacking  the 
plant,  into  a  number  of  groups,  as  follows: 

1.  Boot-feeding  insects,  which  attack  the  roots  of  plants;  they  may 
devour  the  roots,  suck  the  sap,  or  cause  swellings  to  form;  and  the  same 
insect  may  even  attack  the  plant  above  ground  as  well  as  on  the  roots. 

2.  Boring  insects,  which  live  within  the  plant  and  mostly  attack  the 
stem  or  trunk,  but  may  also  bore  into  the  larger  roots  on  the  one  hand 
and  into  the  interior  of  leaves  and  fruit  on  the  other. 

3.  Sap-sucking  insects,  which  attack  the  upper  parts  of  the  plant, 
puncturing  the  leaves  and  stems  to  obtain  their  food.  These  resemble 
the  forms  that  suck  the  sap  from  the  roots,  but  the  latter  are  a  different 
and  much  more  difficult  economic  problem. 

4.  Defoliating  insects,  which  eat  up  the  leaves  and  other  green  parts 
of  plants. 

5.  External  fungi,  growing  over  and  living  upon  the  exposed  parts 
of  the  leaves  and  stems  of  plants,  and  only  sending  feeding  suckers 
into  the  plant. 

6.  Local  fungi,  which  enter  the  plant,  but  remain  at  the  point  where 
they  found  an  entrance,  and  only  spread  by  the  spores,  which  corre- 
spond to  seed,  being  carried  to  other  parts  of  the  leaf  or  plant  and  there 
growing  into  the  plant  again. 

7.  Penetrating  fungi,  which  have  the  power  of  passing  from  one  part 
of  a  plant  to  another  by  boring  their  way  right  through  the  plant. 

Each  of  these  classes  of  pests  must  be  treated  in  a  different  way,  and 
usually  the  remedy  for  one  would  be  entirely  useless  if  applied  for  a 
pest  of  another  class. 

INSECTS. 

Root-Feeding  Insects. — Fortunately  the  number  of  root-feeding  insects  is 
not  large,  for  there  is  no  application  known,  that  is  practical  for  general 
use,  by  which  they  can  be  treated.  It  is  not  that  the  insects  are  hard  to 
kill,  but  that  the  nature  of  the  soil  is  such  that  it  is  very  difficult  to  reach 
them.  The  best  of  the  known  processes — the  use  of  carbon  bisulphid — is 
not  certainly  effectual,  unless  used  in  such  quantity  as  to  destroy  at  the 
same  time  the  roots  of  the  plants;  and  thus  is  practically  useless,  except 
for  disinfecting  soils.  The  very  exhaustive  and  unsuccessful  experiments 
made  with  the  phylloxera,  especially  in  France,  make  it  appear  doubt- 
ful if  anything  will  ever  be  found  in  the  way  of  treatment  for  root  insects. 

The  solution  of  the  problem  for  trees  and  vines  seems  to  be  along  the 
line  of  the  use  of  resistant  roots. 

For  annual  crops,  the  most  promising  methods  at  present  known  are 
crop  rotation,  starvation,  and  trapping. 

The  crop  rotation  method  depends  for  its  success  upon  the  fact  that 
most  of  the  injurious  root- feeding  insects  or  worms  are  decidedly  more 
numerous  in  a  certain  field  in  certain  years,  and  especially  after  certain 
crops.  By  planting  only  those  crops  that  are  the  least  injured  by  the 
attacks  in  the  years  following  these  crops,  the  injury  can,  to  some  degree, 
be  avoided.     Local  experience  will  show  the  particular  system  of  rota- 


—  5  — 

tion  which  will  give  the  best  results  with  the  insects  most  abundant  in 
that  particular  region. 

The  starvation  method  is  by  clean  fallowing  the  land,  and  is  not  par- 
ticularly useful  after  a  crop  like  potatoes,  where  there  is  left  considerable 
living  vegetable  matter  in  the  soil.  It  is  the  most  thorough  method  if 
everything  is  kept  off  the  ground,  and  can  be  used  to  advantage  in  con- 
nection with  trapping. 

The  trapping  method  consists  of  providing  food  for  the  insects  which 
has  first  been  treated  with  a  strong  dose  of  poison.  It  is  especially 
useful  in  gardens  where  root-feeding  insects  are  often  a  very  serious  pest. 
Any  green  food  will  do  for  traps.  Alfalfa  is  commonly  used.  It  is  scat- 
tered around  in  small  piles  and  may  be  partly  covered  with  soil  to  pre- 
vent it  from  drying  out  too  fast. 

Boring  Insects. —About  the  only  thing  that  can  be  done  for  boring 
insects  is  to  prevent,  by  some  means,  their  entrance  into  the  plant. 
This  may  be  done  by  mechanical  means,  by  covering  the  threatened 
parts  with  something  which  will  either  prevent  the  egg-laying  or  form 
a  barrier  to  the  young  insect.  Thus,  the  use  of  cylinders  of  wire  mos- 
quito net,  an  inch  or  two  larger  than  the  trunk  of  the  trees,  is  an 
effectual  bar  against  the  borer  that  attacks  the  butts  of  peach  trees. 
Borers  may  also  be  prevented  entrance  by  coating  the  part  of  the  plant, 
liable  to  attack,  with  a  poisonous  substance,  which  will  be  eaten  by  the 
young  borer  as  it  attempts  to  burrow  into  the  plant.  Such  a  coating  for 
the  trunks  of  trees  is  a  paint  composed  of  glue  made  green  with  Paris 
green.  For  green  parts  of  plants,  especially  against  fruit  insects,  Paris 
green  is  applied  in  water  and  the  application  must  be  repeated  often 
enough  to  keep  the  parts  well  poisoned. 

After  the  insects  have  entered  the  plant,  about  the  only  thing  remain- 
ing to  be  done  is  to  dig  them  out  one  by  one,  though  for  some  living 
very  near  the  surface  it  is  said  that  scalding  hot  water  applied  freely  to 
the  trunk  will  destroy  the  insect  without  injury  to  the  tree. 

It  is  doubtful,  however,  if  by  either  of  these  means  enough  injury  is 
not  directly  or  indirectly  done  to  the  plant  to  more  than  equal  the  good 
attained. 

Sap-Sucking  Insects. — In  this  category  are  included  some  of  the  easiest 
as  well  as  some  of  the  most  difficult  insects  to  destroy,  but  they  are  all 
capable  of  successful  treatment,  so  far  as  we  know.  It  may  often  be, 
however,  that  the  cost  of  a  treatment  which  is  effective  will  be  so  great 
as  to  be  prohibitive.  This  is  true  generally  of  field  crops,  where  the  cost 
per  acre  for  treatment  may  often  be  more  than  the  saving  that  can  ensue 
from  the  application.  The  insects  of  this  class  are  not  affected  by 
poisons  like  Paris  green,  because  they  get  their  food  by  inserting  their 
beak  into  the  plant;  nothing,  therefore,  on  the  surface  of  the  leaves  will 
have  any  particular  effect. 

There  have  been  many  attempts  at  injecting  some  substance  into  the 
plant  which  will  poison  the  sap,  but  the  cells  of  the  plant  are,  if  any- 
thing, more  delicate  than  the  insect,  so  that  the  plant  is  always  killed 
first. 

The  only  feasible  plan,  therefore,  is  to  spray  on  them  some  caustic 
or  oily  substance,  or  to  envelop  them  with  some  poisonous  gas. 

Plant-lice  are  ordinarily  very  easy  to  kill,  but  protected  insects,  like 


—  6  — 

the  scale  insects,  or  very  active  ones,  like  the  so-called  grape  thrips,  are 
much  more  difficult  to  deal  with.  The  latter  are  probably  best  treated 
by  causing  them  to  leap  or  fly  against  a  "  hopper  doser"  of  some  form. 
A  hopper  doser  consists  of  a  surface  of  tin,  or  other  material,  covered 
with  tar,  printer's  ink,  or  some  other  sticky  substance,  which  will  hold 
captive  the  insects  touching  it. 

Defoliating  Insects. — The  insects  eating  the  leaves  of  plants  are,  as  a 
rule,  the  easiest  insects  to  destroy,  and  at  the  least  expense,  because  the 
leaves  may  be  covered  with  relatively  cheap  poisonous  substances;  and 
as  the  insects  eat  the  leaf,  they  will  also  consume  the  poison  and  be 
killed.  Only  the  more  valuable  field  crops  can  be  treated  economically, 
however,  for  even  as  cheap  a  process  as  this  is  too  expensive  for  most  of 
the  staple  crops. 

When  insects  are  excessively  abundant,  as  in  the  case  of  attacks  of 
locust  swarms  and  invasions  of  army  worms,  all  known  applications 
become  useless,  because  with  their  great  numbers  everything  green  is 
devoured  before  any  one  insect  can  have  taken  enough  poison  to  kill  it. 

Insects  of  the  defoliating  class  can  also  be  killed  by  the  same  remedies 
used  for  sap-sucking  forms;  but  with  those  remedies,  as  is  true  of  the 
insects  of  the  former  class,  the  insect  must  actually  be  touched  by  the 
remedy  to  be  affected  by  it. 

FUNGI. 

External  Fungi. — The  molds  or  mildews  occurring  on  the  leaves  of 
plants  in  this  State  belong  almost  exclusively  to  this  class  of  fungi. 

One  can  easily,  with  the  aid  of  a  small  microscope,  see  the  threads  of 
the  fungus.  All  parts  of  the  plant  above  ground  are  affected,  but  the 
young  leaves  and  the  ends  of  stems  are  most  readily  attacked. 

They  may  be  destroyed  and  the  spread  of  the  fungus  stopped  by  the 
use  of  the  vapor  of  sulphur. 

Local  Fungi. — Most  of  the  rusts  and  spot  fungi  may  be  classed  under 
this  head.  They  live  within  the  plant,  and  so  cannot  be  destroyed 
after  they  once  gain  an  entrance.  A  cure,  therefore,  is  impossible",  and 
attention  must  be  turned  to  preventing  their  entrance.  The  spores 
are  produced  very  abundantly  and  quickly  in  most  species,  so  that,  if 
treatment  is  not  given  soon  after  the  first  appearance  of  the  trouble,  it 
will  be  seen  to  spread  with  great  rapidity  and  involve  a  much  larger 
part  of  the  plant. 

The  theory  of  treatment  is  to  keep  the  plant  covered  with  some  sub- 
stance which  will  prevent  the  germination  or  sprouting  of  the  spores, 
thus  preventing  the  fungus  from  entering  a  new  part  of  the  plant.  We 
now  know  a  number  of  very  effectual  substances  which  will  produce 
this  result. 

Penetrating  Fungi. — This  is  the  most  difficult  group  of  fungi  we  have 
to  deal  with.  Grain  smuts,  blackberry  rust,  and  curl-leaf  of  the  peach 
are  examples.  In  annual  plants  the  infection  usually  occurs  at  about 
the  time  that  the  seed  sprouts,  so  that  the  destruction  of  the  spores 
that  may  be  on  the  seed  is  often  sufficient  to  insure  practical  immunity. 

In  perennials,  the  only  thing  usually  to  be  done  is  the  removal  and 
destruction  of  the  infested  plants. 


Some  diseases  of  trees  due  to  these  fungi  may  possibly  be  controlled 
by  preventing  the  spread  of  the  disease  (by  spores),  by  the  use  of  the 
remedies  that  are  so  effectual  against  the  local  fungi,  and  by  vigorous 
pruning  and  removing  the  new  growth,  in  which  the  disease  is  chiefly 
carried  over  from  one  season  to  another.  This  is,  at  least  at  present, 
the  most  promising  line  of  experiment  in  these  cases. 

The  experience  in  some  parts  of  this  State  with  curl-leaf,  where  it 
seems  to  be  entirely  controllable,  would  seem  to  indicate  that  the  disease 
is  not,  in  every  region,  to  be  properly  classed  with  these  penetrating 
fungi. 

Further  study  may  show  that  other  fungi  may,  in  certain  seasons  or 
in  certain  regions,  be  a  local  and  in  others  a  penetrating  fungus,  and  so 
in  one  place  be  easily  controlled,  and  in  another  not  at  all  controllable 
without  the  destruction  of  the  plants  affected. 


REMEDIES. 

There  are  a  great  many  substances  that  may  be  used  successfully 
against  insects  and  fungi;  but  we  recommend  only  a  small  list,  selected 
because  of  their  effectiveness  and  cheapness.  Remedies  are  applied  as 
a  dry  powder,  as  a  gas,  or  as  a  fluid,  spray  or  wash;  the  great  majority 
being  in  the  latter  form. 

Powders. — The  most  common  way  of  applying  powders  is  the  "  pepper- 
box "  method,  in  which  the  material  is  carried  in  a  vessel  provided 
with  perforations,  through  which  it  sifts  as  the  vessel  is  shaken  over  the 
plant.  A  modification  of  this,  much  used  in  the  cotton  fields  of  the 
Southern  States,  consists  of  bags  of  the  material  suspended  from  the 
ends  of  a  pole  long  enough  to  reach  from  one  row  of  cotton  to  the  next. 
This  is  carried  by  a  man  riding  on  a  mule,  and  the  jar  causes  the 
powder  to  sift  through.  Cloth  is  chosen  for  this  purpose  which  is  fine 
enough  to  allow  only  the  right  quantity  to  be  distributed.  A  third 
method,  much  used  in  this  country,  is  a  blowing  device,  which  is  very 
satisfactory  for  field  use,  and  does  very  rapid  work.  Only  three  reme- 
dies are  recommended  to  be  used  in  the  dry  form,  and  these  have  a  rather 
limited  use. 

Air-Slaked  Lime. — This  is  the  powder  resulting  from  the  exposure 
of  ordinary  lime  to  the  action  of  the  air  for  some  time.  It  is  only 
recommended  as  a  remedy  against  insects  which  have  a  slimy  coating 
over  the  body.  For  these  it  is  a  cheap  and  effectual  remedy.  It  is  not 
as  cheap,  however,  as  Paris  green,  and  is  particularly  recommended 
where  the  latter  is  objectionable  because  of  its  poisonous  nature. 

For  true  slugs,  which  are  not  insects,  but  have  a  similar  slimy  coat, 
it  is  the  best  remedy  we  know  of ;  but  it  must  be  applied  in  the  evening 
or  early  morning,  while  the  animals  are  on  the  plants;  and  may  have 
to  be  repeated  two  or  three  nights  in  succession  to  kill  all.  Except  in 
gardens,  it  may  not  pay  to  make  more  than  the  one  application,  which 
will,  if  rightly  timed,  destroy  most  of  the  slugs. 

Sulphur. — This  is  a  widely  used  remedy  for  the  mildew,  which  is  so 
common  on  plants  in  this  State.  The  powder  is  usually  applied  by  the 
pepper-box  method.     It  only  becomes  effectual  as  the  heat  of  the  sun 


—  8  — 

vaporizes  it;  the  field  thus  treated  smells  strongly  of  the  sulphur  during 
the  warmer  part  of  the  day,  when  the  vapor  is  being  produced.  On  wet, 
cloudy  days,  when  the  mildew  is  growing  and  spreading  rapidly,  the 
sulphur  is  inert,  but  the  first  bright  day  makes  it  effective.  It  may  be 
possible  to  artificially  vaporize  the  sulphur  on  a  large  scale  for  use  in 
such  weather;  but  no  attempt  has  yet  been  carefully  made,  except  in 
greenhouses,  and  then  with  the  best  of  results.  The  vapor  of  sulphur 
must  be  used,  and  not  the  gas  produced  by  burning,  which  is  very  inju- 
rious to  foliage. 

Sulphur  has  been  found  to  be  a  successful  remedy  for  the  so-called 
red  spiders,  also  called  yellow  mite — animals  somewhat  related  to  the 
true  insects;  fairly  good  results  are  also  reported  in  its  use  against  the 
thrips.  For  these  purposes  the  sulphur  is  used  in  the  same  way  as  for 
the  mildew. 

Paris  Green  or  London  Purple* — These  two  arsenical  poisons  are  occa- 
sionally used  in  a  dry  form,  but  chiefly  suspended  in  water  as  a  spray. 
They  are  used  for  the  same  purposes  in  either  form.  A  common  prac- 
tice is  to  dilute  the  poison  with  flour,  dust,  or  other  powder,  so  that  it 
can  be  more  easily  and  evenly  distributed.  If  not  so  diluted,  care  must 
be  taken  not  to  apply  it  so  thickly  in  places  as  to  endanger  the  foliage. 

Gas  Treatments. 

Gases  have  the  property  of  diffusing  themselves  with  great  rapidity, 
so  that  when  applied  in  a  closed  space  every  part  of  that  space  will  in  a 
short  time  contain  some  of  the  gas.  Thus,  no  other  method  of  killing 
insects  is  calculated  to  be  as  thorough  in  its  work.  In  an  open  space 
this  property  of  diffusing  destroys,  to  a  great  extent,  its  utility.  Sulphur 
applied  as  a  powder,  as  has  already  been  stated,  is  not  effective  until  it 
becomes  a  vapor;  and  then  the  dissipation  is  not  as  much  as  with  most 
gases,  because  of  the  weight  of  sulphur  vapor  and  the  fact  that  it  is 
applied  over  whole  fields  at  once. 

The  impracticability  of  inclosing  most  cultivated  plants,  and  the  cost 
of  the  treatment,  both  in  time  and  chemicals,  makes  the  method  useful 
to  only  a  very  limited  extent.     We  recommend  but  two  gases. 

Carbon  Bisulphid. — This  substance  is  not  available  for  plants  in 
active  growth,  and  is  chiefly  useful  for  stored  products,  such  as  seeds 
and  grains.  It  can  be  used  for  disinfecting  soils  and  ridding  other 
articles  of  insects. 

In  disinfecting  soils  an  injector  is  used.  A  number  of  forms  of  the 
latter  are  on  the  market  in  Europe,  where  phylloxera  eradication  has 
required  them.  It  is  doubtful  if  this  method  of  soil  disinfection  would 
be  profitable  in  this  country  for  the  destruction  of  any  insect. 

For  destroying  insects  in  seeds  or  grain,  carbon  bisulphid  is  a  very 
cheap  and  satisfactory  means.  The  bin  or  box  containing  the  seeds  to 
be  disinfected  should  be  tight,  at  least  at  the  sides  and  below. 

A  dish  is  placed  on  top  of  the  material  to  be  treated,  and  a  quantity 
of  the  carbon  bisulphid  poured  in.  This  evaporates  rapidly,  and  the 
vapor,  being  heavier  than  air,  sinks  down  into  the  lower  part  of  the  bin. 


*For  a  general  account  of  their  action,  see  under  sprays. 


—  9  — 

The  top  should  be  covered  also,  in  order  that  the  vapor  may  remain  a 
long  time  in  the  grain. 

Very  rarely  will  bins  be  perfectly  tight,  so  that  the  exact  amount 
necessary  cannot  be  stated.  Usually  the  estimate  is  made  at  one  pound 
to  the  ton  of  grain,  which  is  sufficient  for  a  fairly  tight  bin. 

Grapevine  cuttings  are  most  successfully  disinfected  in  a  similar  way, 
by  placing  a  saucerfull  of  the  bisulphid  on  the  cuttings  in  a  tight  box, 
and  leaving  for  forty  minutes. 

The  yellow  jacket,  our  common  wasp,  which  is  so  injurious  to  fruit, 
and  which  makes  its  nest  in  the  ground,  is  easily  killed  by  this 
substance.  The  nest  is  located,  and  about  dark,  when  the  wasps  are  all 
in,  about  an  ounce  of  carbon  bisulphid  is  poured  down  the  hole  and  a 
handful  of  earth  thrown  over  it  to  keep  the  vapor  in.  By  morning  all 
will  be  found  to  be  dead.     Ants'  nests  can  be  destroyed  in  the  same  way. 

Carbon  bisulphid  is  also  one  of  the  best  remedies  for  gophers.  If  used 
in  the  fall,  after  the  rains  have  begun  (so  that  the  ground  is  not  too 
porous),  an  ounce  poured  over  a  rag  and  stuffed  into  a  hole  and  covered 
with  earth  will  destroy  the  inmates. 

Hydrocyanic  Acid  Gas. — This  is  practically  the  only  gas  which  is 
strong  enough  to  kill  the  insects  on  a  tree  with  safety  to  the  leaves,  and 
within  a  time  short  enough  to  make  its  use  practical  on  a  large  scale.  Its 
work  is  very  effectual  and  satisfactory,  but  is  very  expensive,  and, 
therefore,  is  only  available  for  the  more  profitable  trees,  such  as  the 
citrus  varieties.  It  may  also  be  used  for  disinfecting.  The  gas  is 
extremely  poisonous,  and,  sometimes,  for  reasons  not  entirely  under- 
stood, is  very  injurious  to  the  foliage;  but  the  injury  is  almost  all 
prevented  by  its  use  at  night. 

The  process  is  to  cover  the  tree  with  a  tent  of  sail-cloth,  oiled  to  make 
it  tight,  and  in  a  vessel  beneath  the  tent  the  chemicals  which  make  the 
gas  are  placed.  After  half  an  hour  the  tent  is  removed  and  put  over 
the  next  tree.  The  chemicals  needed  for  every  100  cubic  feet  are  -J 
ounce  of  potassium  cyanide,  §  ounce  of  water,  and  i  ounce  of  sulphuric 
acid. 

The  common  practice  in  this  State  is  to  use  it  decidedly  stronger  for 
small  trees  and  weaker  for  the  largest  trees.  In  the  smaller  trees  it  is 
safe  to  use  it  stronger,  as  the  small  amount  of  gas  used  is  very  quickly 
diffused.  When  it  is  produced  in  large  quantity,  as  is  necessary  for 
a  large  tree,  some  of  the  gas,  scarcely  at  all  mixed  with  air,  may  come  in 
contact  with  the  leaves  and  injure  them.  The  practice  probably  arose,  in 
part,  from  some  tables  which  have  been  published  widely  in  this  State, 
where  the  contents  of  the  tent  was  calculated  by  multiplying  the  height 
of  the  tree  by  its  breadth.  The  practice  is  not  justifiable,  and  if  the 
weaker  amount  is  successful  there  is  no  reason  for  not  using  the  same 
proportion  on  smaller  trees. 

There  are  many  kinds  of  tents  used,  and  many  plans  for  changing 
them  from  tree  to  tree,  the  details  of  which  we  cannot  give  here.  The 
tent  is  usually  of  an  octangular  shape,  and  is  furnished  with  rings  for 
hoisting.     The  largest  tents  require  a  derrick  for  lifting  them  into  place. 


—  10  — 

The  following  are  the  amounts  of  cyanide  of  potash  to  be  used  for  trees 
of  varying  heights: 


Amount  of  Cyanide  of  Potash. 

Height  of  Tree. 

If  as  broad  as 

high  (Navel 

Oranges,  etc.) 

If  %  as  broad  as 
high  (Seedling 
Oranges,  etc.) 

jounce .- 

6  feet. 

8  feet. 
10  feet. 
12  feet. 
15  feet. 
19  feet. 

8  feet. 

1  ounce __     .  

10  feet. 

2  ounces  .  . 

12  feet. 

4  ounces  .     -     

15  feet. 

8  ounces __ 

20  feet. 

lpouncL.       .     - - 

28  feet. 

SPRAYS    OR    WASHES. 


The  most  important  remedies  for  plant  pests  are  applied  as  a  spray 
or  wash.  By  the  word  wash  one  would  naturally  understand  a  more 
copious  application  than  a  spray,  but  in  ordinary  usage  the  terms  are 
identical. 

For  very  low  plants  an  outfit  working  on  the  principle  of  a  sprinkling- 
can  will  do;  but  for  better  and  more  economical  work,  and  work  on 
higher  plants,  some  form  of  force-pump  and  spray  nozzle  is  necessary. 

There  are  many  forms  of  pumps  on  the  market  that  are  good  for  the 
purpose.  A  good  spray  pump  should  maintain  a  fairly  constant  and 
sufficient  pressure,  and  its  valves  and  general  construction  should  be 
simple  and  its  parts  easily  replaceable. 

The  nozzle  should,  for  most  spraying  work,  be  such  as  to  break  up  the 
stream  into  a  fine  mist;  but  for  scale  insects  one  giving  a  stream  of  con- 
siderable force  is  desirable.  The  shape  of  the  spray  is  usually  either 
conical  or  fan-shaped,  and  each  has  its  particular  advantages  for  a  par- 
ticular class  of  work. 

The  construction  of  the  nozzle  should  be  such  as  to  permit  of  easy, 
quick,  and  thorough  cleaning.  A  few  forms  designed  to  clean  themselves 
automatically,  work  well. 

In  most  spraying  the  object  is  to  get  the  largest  possible  proportion  of 
the  spray  to  remain  on  the  leaf  or  stem,  and  to  have  it  well  distrib- 
uted. This  is  best  accomplished  by  covering  the  leaf  with  minute 
globules  like  dew.  As  soon  as  they  run  together  and  drip  from  the 
leaf  the  distribution  is  not  perfect,  and  there  is  actually  less  left  on  the 
leaves. 

When  the  nozzle  is  held  as  far  from  the  plant  as  the  stream  will  carry, 
the  full  effect  of  the  nozzle  is  obtained  in  the  breaking  up  of  the  stream 
into  mist,  and  so  can  produce  most  perfectly  this  dew-like  condition. 

For  scale  insects  the  object  is  somewhat  different.  The  plan  for  these 
is  to  thoroughly  wet  the  surface  of  the  bark  and  the  edges  of  the  scale, 
to  insure  the  penetration  of  the  wash  beneath  the  scale,  and  thus  to  kill 
the  old  scale  or  the  eggs  and  young  hidden  beneath.  This  thorough 
wetting  is  secured  by  holding  the  nozzle  close  to  the  plant  and  applying 
a  great  deal  of  the  wash  with  a  high  pressure.  Washes  are  sometimes 
applied  hot,  and  when  the  nozzle  is  held  close  to  the  plant  the  spray 
will  penetrate  better,  and  for  this  reason  do  better  work. 


—  11  — 

Heat  is  to  be  recommended  as  a  remedy  only  when  it  can  be  abso- 
lutely controlled. 

Grain  Smut. — The  method  of  treating  seed  wheat  and  oats  for  smut 
is  as  follows: 

For  wheat,  soak  fifteen  minutes  in  water  at  132°  F.;  for  oats,  ten 
minutes.  The  grain  should  first  be  placed  in  water  at,  say,  115°,  to 
partly  warm  it  up.  See  that  the  grain  is  all  wetted  and  do  not  treat 
too  much  at  a  time,  or  it  will  be  impossible  to  keep  the  water  at  the 
proper  temperature.  Have  boiling  and  cold  water  at  hand,  so  as  to  add 
to  keep  the  temperature  just  right.  It  must  not  go  above  135°,  or  it 
may  injure  the  seed;  nor  below  130°,  or  it  will  not  be  effective.  After 
treating,  dip  in  cold  water  to  cool,  and  spread  out  to  dry. 

Bordeaux  Mixture. — This  is  the  most  used  and  the  most  satisfactory  of 
the  known  washes  for  prevention  of  fungous  attacks.  When  sprayed 
upon  the  plant  it  prevents  the  development  of  the  spores  of  any  fungi 
upon  the  surface  covered;  and  it  is  thus  a  perfect  preventive  of  all  the 
fungi  which  gain  an  entrance  to  the  plant  in  this  way.  To  be  effective 
it  must  be  kept  continuously  on  the  plant  that  is  to  be  protected.  A 
single  spraying  will  last  from  two  weeks  to  a  month,  or  even  longer  if 
the  conditions  are  favorable.  With  our  dry  summers  one  application 
will  often  be  found  enough  for  some  kinds  of  fungi. 

Late  spring  rains  may  make  additional  sprayings  necessary;  and 
some  fungi  may,  in  some  localities,  require  the  repeated  sprayings  neces- 
sary in  a  more  humid  climate.  Local  experience  will  have  to  determine 
these  points. 

Bordeaux  mixture  is  made  of  equal  parts  of  bluestone  (copper  sul- 
phate) and  lime.  Some  formulas  give  6  parts  of  bluestone  to  4  parts 
of  lime,  and  will  do  if  the  lime  is  good.  Slake  the  lime,  and  dissolve 
the  bluestone  separately.  Both  should  be  cold  when  they  are  mixed, 
and  the  resultant  mixture  will  be  a  beautiful  blue  wash.  If  mixed  hot, 
a  black  compound  (copper  oxide)  is  produced,  which  reduces  the  value 
of  the  wash. 

As  to  the  amount  of  water,  we  recommend,  for  ordinary  spraying,  1 
pound  of  each  of  the  above  to  10  gallons  of  mixture;  and  for  winter 
use,  1  pound  of  each  for  4  gallons. 

Ammoniacal  Copper  Carbonate. — This  solution  is  very  effectual,  but 
is  not  as  lasting  as  the  Bordeaux  mixture.  It  is  a  perfect  solution,  and 
therefore  has  no  tendency  to  clog  the  nozzle  (as  is  the  case  with  the 
Bordeaux  mixture),  and  can  be  used  on  fruit  near  the  picking  season, 
and  on  ornamental  plants,  which  would  be  disfigured  with  the  lime  wash. 

The  usual  way  of  making  this  wash  is  to  dissolve  copper  carbonate  in 
ammonia,  and  then  dilute.  If  the  carbonate  is  not  fully  dissolved  before 
the  water  is  added  it  cannot  be  further  dissolved,  and  not  only  is  the 
carbonate  wasted,  but  the  fluid  will  not  be  up  to  standard  strength.  It 
is  well,  therefore,  to  give  the  ammonia  ample  time  to  act,  say  over  night, 
before  adding  the  water.  The  proportions  are  1  ounce  of  the  copper 
carbonate  in  10  ounces  of  ammonia  for  every  10  gallons  of  spray. 

Another  way  of  producing  the  mixture  is  to  mix  solutions  of  bluestone 
and  sal  soda,  dissolving  the  carbonate  of  copper  thus  produced  in 
ammonia,  and  diluting  with  water.     The  bluestone  and  the  sal  soda 


—  12  — 

should  be  mixed  in  about  the  proportion  of  3  to  4,  after  having  been 
dissolved  separately  in  a  small  quantity  of  warm  water,  and  cooled 
before  mixing. 

Three  ounces  of  bluestone  with  4  of  sal  soda  and  20  of  ammonia  is 
sufficient  for  20  gallons  of  spray. 

Lime,  Salt,  and  Sulphur  Mixture. — This  wash  is  useful  both  as  an 
insecticide  and  a  fungicide,  but  only  for  winter  use  on  deciduous  trees. 

It  is  usually  made  by  boiling  the  sulphur  for  one  hour  and  a  half 
with  about  one  fourth  of  the  lime,  in  a  covered  kettle,  with  enough  water 
to  cover  well;  then  the  rest  of  the  lime  and  the  salt  are  added,  and  the 
boiling  continued  half  an  hour  longer. 

The  proportions  are  about  6  pounds  of  lime,  2  of  salt,  and  3  of  sul- 
phur, for  60  gallons. 

Resin  Soap. — The  cheapest  insecticide  which  kills  by  contact  is  resin 
soap.  It  is  for  scale  insects,  and  so  has  good  penetrating  power.  Like 
all  insecticides  killing  by  contact,  the  effect  of  the  spray  is  soon  gone,  and 
it  only  kills  the  insects  which  are  wet  with  its  spray.  It  is  generally 
applied  warm. 

In  making  the  soap,  the  ingredients  are  placed  in  a  closed  kettle  with 
enough  water  to  cover,  and  are  boiled  for  two  hours,  when  all  will  be 
united  into  a  soap.  In  diluting,  only  a  little  water  should  be  added  at 
a  time,  and  stirred  in;  or,  better,  hot  water  should  be  used,  because  of  the 
danger  of  chilling  the  soap  and  causing  it  to  harden,  when  it  is  almost 
impossible  to  dissolve  it  again. 

The  proportions  are  8  pounds  of  resin,  2  pounds  of  standard  caustic 
soda,  and  1  pint  of  fish  oil  for  40  gallons,  for  use  on  trees  in  foliage; 
and  the  same  for  25  to  30  gallons  for  winter  use. 

Kerosene. — There  has  recently  been  placed  on  the  market  devices  for 
mixing  kerosene  with  water  in  the  pump  as  it  is  being  applied;  and 
with  very  good  results.  Full  directions  as  to  proportions  accompany 
the  device,  and  we  will  here  only  discuss  the  precautions  to  be  observed. 
These  are,  chiefly,  the  use  of  a  nozzle  capable  of  producing  a  very  fine 
mist;  and  applying  the  spray  so  that  the  drops  do  not  run  together,  i.  e., 
holding  the  nozzle  as  far  as  possible  from  the  plant,  and  not  applying 
too  much. 

Pure  kerosene  has  great  penetrating  power,  perhaps  the  greatest  of  all 
the  insecticides,  and  with  the  above  precautions  can  be  safely  used. 

Kerosene  Emulsion. — While  not  as  cheap  as  resin  soap,  kerosene 
emulsion  is  easier  to  make;  and,  in  small  quantities,  or  where  the  con- 
veniences for  boiling  are  not  at  hand,  is  the  most  satisfactory  remedy. 
Like  resin  soap,  this  spray  only  kills  by  contact. 

The  ordinary  form  of  the  emulsion  is  something  of  an  art  to  properly 
manufacture.  The  ingredients  are  2  parts  of  kerosene  to  1  of  sour 
milk,  or  of  strong  soap  solution.  The  latter  must  be  made  boiling-hot 
and  added  to  the  kerosene,  and  the  whole  pumped  through  a  spray 
nozzle  for  fifteen  minutes.  After  pumping  a  few  minutes  the  whole 
mass  will  become  beautifully  creamy  and  apparently  perfectly  emulsi- 
fied; but  if  a  little  is  placed  in  water  it  will  be  seen  that  some  of  the 
kerosene  separates  out  and  rises  to  the  surface.     When  the  emulsion  is 


—  13  — 

perfect  there  will  be  no  separation  when  diluted.  If  the  soap  is  of  poor 
quality  or  the  water  is  hard,  more  soap  must  be  used;  and,  on  the  other 
hand,  if  both  are  good  not  as  much  is  needed  as  recommended  below, 
which  is  intended  to  suit  the  average  condition. 

The  proportions  are  3  ounces  of  soap  in  3  pints  of  water  or  sour 
milk,  and  3  quarts  of  kerosene  for  10  gallons  of  emulsion  for  scale  insects, 
or  for  15  gallons  for  plant-lice. 

Another  formula,  which  is  easier  made  but  more  expensive,  and  so  only 
recommended  for  use  on  a  small  scale,  consists  of  using  eight  times  as 
much  soap.  When  so  made,  the  creamy  mixture  described  above, 
obtained  within  five  minutes,  is  a  permanent  emulsion. 

Paris  Green  and  London  Purple. — These  poisons  kill  only  those  insects 
that  eat  the  leaves  covered  by  them,  and  are  useless  against  sucking 
insects  like  plant-lice  and  scales.  They  are  also  useless  against  over- 
whelming numbers  of  insects,  such  as  swarms  of  grasshoppers,  which  are 
able  to  eat  up  the  plant  before  getting  enough  poison  to  kill  them. 

Arsenic  is  the  active  principle  in  both  these  poisons,  and  is  about 
equally  strong  in  both.  Paris  green  is  copper  arsenite,  and  London 
purple  an  arsenite  of  lime  containing  an  aniline  residue,  to  which  the 
purple  color  is  due.  The  latter  is  a  finer  powder  and  remains  better 
suspended  in  water,  but  the  Paris  green  is,  as  a  rule,  safer  to  apply. 
Both  poisons,  if  applied  too  strong,  will  burn  the  foliage,  and  both 
require  constant  stirring,  or  the  material  will  settle  to  the  bottom,  and 
so  not  be  uniformly  distributed.  For  the  best  results,  the  poison  should 
not  be  allowed  to  drip  from  the  tree,  and  the  finer  the  spray  the  better. 

These  poisons  do  not  as  a  rule  remain  any  great  length  of  time  on  the 
plant,  but  must  be  renewed  every  two  or  three  weeks,  or  while  the 
danger  of  insect  attack  exists.  In  mixing  the  poison  it  is  well  to  first 
make  a  paste  with  a  little  water  and  then  dilute,  as  otherwise  it  is  diffi- 
cult to  wet  the  leaves  with  it.  The  amount  used  is  about  one  pound  to 
two  hundred  gallons  of  water. 


14 


THE    TABLE. 


The  following  table  is  intended  to  give,  in  a  glance  and  in  small 
compass,  the  ingredients,  proportions,  and  method  of  preparation  of 
these  various  washes.  For  convenience  they  are  calculated  in  per  cents 
for  metric  calculations;  while  the  amounts  necessary  for  5  and  40  gal- 
lons respectively  (as  representing  an  oil-can  and  barrel)  are  given  in 
the  common  weights  and  measures.  The  table  should  be  tacked  up  and 
preserved  for  future  reference: 


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